The Monetary Authority of Singapore (MAS) has been closely monitoring the exposure and losses incurred by broking houses here after the spectacular crash of three penny stocks.

Blumont Group, Asiasons Capital and LionGold Corp had billions of dollars wiped out in market value, which triggered the Singapore Exchange (SGX) to suspend its trading on Oct 4.

The suspension was lifted three days later, but the counters were labelled as "designated securities". This meant that investors had to buy into these shares with cash, and could only sell them when they received the scripts to them.

The designation led to what industry players called "panic selling" as players dumped their stakes into the market.

Responding to media queries, the MAS said that it "has been closely monitoring the exposure of the broking firms by collecting reports on losses and major counterparty exposure arising from their exposures to the three counters."

"The operations and financial positions of the broking firms remain sound (and we) will continue to monitor the situation closely."

With over $8 billion in market value wiped out in under a week, there were calls for the SGX and MAS to better protect investors and review current trading and market practices.

An MAS spokesman said that: "MAS and SGX are conducting an extensive review of the activities around these stocks."

Further information cannot be released at this point as it may undermine potential investigations.

But it also said that this episode has "surfaced broader issues regarding the market structure and practices which MAS and SGX intend to review thoroughly."

It will consult the public after the review, if changes are required.